Add ProtocolApi module

client/android/protocolApi/src/main/kotlin/Protocol.kt

@@ -0,0 +1,115 @@
+package org.amnezia.vpn.protocol
+
+import android.annotation.SuppressLint
+import android.content.Context
+import android.net.IpPrefix
+import android.net.VpnService
+import android.net.VpnService.Builder
+import android.os.Build
+import android.system.OsConstants
+import androidx.annotation.RequiresApi
+import java.io.File
+import java.io.FileOutputStream
+import java.util.zip.ZipFile
+import org.amnezia.vpn.Log
+import org.json.JSONObject
+
+private const val TAG = "Protocol"
+
+const val VPN_SESSION_NAME = "AmneziaVPN"
+
+abstract class Protocol(protected val context: Context) {
+
+    open lateinit var config: ProtocolConfig
+
+    abstract val statistics: Statistics
+
+    abstract fun initialize()
+
+    abstract fun parseConfig(config: JSONObject)
+
+    protected open fun buildVpnInterface(vpnBuilder: Builder) {
+        vpnBuilder.setSession(VPN_SESSION_NAME)
+        vpnBuilder.allowFamily(OsConstants.AF_INET)
+        vpnBuilder.allowFamily(OsConstants.AF_INET6)
+
+        for (addr in config.addresses) vpnBuilder.addAddress(addr)
+        for (addr in config.dnsServers) vpnBuilder.addDnsServer(addr)
+        for (addr in config.routes) vpnBuilder.addRoute(addr)
+
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU)
+            for (addr in config.excludedRoutes) vpnBuilder.excludeRoute(addr)
+
+        for (app in config.excludedApplications) vpnBuilder.addDisallowedApplication(app)
+
+        vpnBuilder.setMtu(config.mtu)
+        vpnBuilder.setBlocking(config.blockingMode)
+        vpnBuilder.setUnderlyingNetworks(null)
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q)
+            vpnBuilder.setMetered(false)
+    }
+
+    abstract fun startVpn(vpnBuilder: Builder, protect: (Int) -> Boolean)
+
+    abstract fun stopVpn()
+
+    companion object {
+        private fun extractLibrary(context: Context, libraryName: String, destination: File): Boolean {
+            Log.d(TAG, "Extracting library: $libraryName")
+            val apks = hashSetOf<String>()
+            context.applicationInfo.run {
+                sourceDir?.let { apks += it }
+                splitSourceDirs?.let { apks += it }
+            }
+            for (abi in Build.SUPPORTED_ABIS) {
+                for (apk in apks) {
+                    ZipFile(File(apk), ZipFile.OPEN_READ).use { zipFile ->
+                        val mappedName = System.mapLibraryName(libraryName)
+                        val libraryZipPath = listOf("lib", abi, mappedName).joinToString(File.separator)
+                        val zipEntry = zipFile.getEntry(libraryZipPath)
+                        zipEntry?.let {
+                            Log.d(TAG, "Extracting apk:/$libraryZipPath to ${destination.absolutePath}")
+                            FileOutputStream(destination).use { outStream ->
+                                zipFile.getInputStream(zipEntry).use { inStream ->
+                                    inStream.copyTo(outStream, 32 * 1024)
+                                    outStream.fd.sync()
+                                }
+                            }
+                        }
+                        return true
+                    }
+                }
+            }
+            return false
+        }
+
+        @SuppressLint("UnsafeDynamicallyLoadedCode")
+        fun loadSharedLibrary(context: Context, libraryName: String) {
+            Log.d(TAG, "Loading library: $libraryName")
+            try {
+                System.loadLibrary(libraryName)
+                return
+            } catch (_: UnsatisfiedLinkError) {
+                Log.d(TAG, "Failed to load library, try to extract it from apk")
+            }
+            var tempFile: File? = null
+            try {
+                tempFile = File.createTempFile("lib", ".so", context.codeCacheDir)
+                if (extractLibrary(context, libraryName, tempFile)) {
+                    System.load(tempFile.absolutePath)
+                    return
+                }
+            } catch (e: Exception) {
+                throw LoadLibraryException("Failed to load library apk: $libraryName", e)
+            } finally {
+                tempFile?.delete()
+            }
+        }
+    }
+}
+
+private fun VpnService.Builder.addAddress(addr: InetNetwork) = addAddress(addr.address, addr.mask)
+private fun VpnService.Builder.addRoute(addr: InetNetwork) = addRoute(addr.address, addr.mask)
+
+@RequiresApi(Build.VERSION_CODES.TIRAMISU)
+private fun VpnService.Builder.excludeRoute(addr: InetNetwork) = excludeRoute(IpPrefix(addr.address, addr.mask))